Add CsvParser.Feature.ALLOW_TRAILING_COMMA to allow enforcing strict handling

src/main/java/com/fasterxml/jackson/dataformat/csv/CsvParser.java

@@ -67,6 +67,15 @@ public enum Feature
          * @since 2.7
          */
         IGNORE_TRAILING_UNMAPPABLE(false),
+
+        /**
+         * Feature that allows there to be a trailing single extraneous data
+         * column that is empty. When this feature is disabled, any extraneous
+         * column, regardless of content will cause an exception to be thrown.
+         * Disabling this feature is only useful when
+         * IGNORE_TRAILING_UNMAPPABLE is also disabled.
+         */
+        ALLOW_TRAILING_COMMA(true),
         ;
 
         final boolean _defaultState;
@@ -730,7 +739,7 @@ protected JsonToken _handleExtraColumn(String value) throws IOException
         // 14-Mar-2012, tatu: As per [dataformat-csv#1], let's allow one specific case
         // of extra: if we get just one all-whitespace entry, that can be just skipped
         _state = STATE_SKIP_EXTRA_COLUMNS;
-        if (_columnIndex == _columnCount) {
+        if (_columnIndex == _columnCount && Feature.ALLOW_TRAILING_COMMA.enabledIn(_formatFeatures)) {
             value = value.trim();
             if (value.isEmpty()) {
                 // if so, need to verify we then get the end-of-record;

src/test/java/com/fasterxml/jackson/dataformat/csv/deser/TrailingCommaTest.java

@@ -0,0 +1,39 @@
+package com.fasterxml.jackson.dataformat.csv.deser;
+
+import com.fasterxml.jackson.annotation.JsonPropertyOrder;
+import com.fasterxml.jackson.databind.JsonMappingException;
+import com.fasterxml.jackson.databind.MappingIterator;
+import com.fasterxml.jackson.dataformat.csv.CsvMapper;
+import com.fasterxml.jackson.dataformat.csv.CsvParser;
+import com.fasterxml.jackson.dataformat.csv.CsvSchema;
+import com.fasterxml.jackson.dataformat.csv.ModuleTestBase;
+
+public class TrailingCommaTest extends ModuleTestBase {
+    final CsvMapper MAPPER = mapperForCsv();
+
+    @JsonPropertyOrder({ "a", "b" })
+    static class StringPair {
+        public String a, b;
+    }
+
+    public void testDisallowTrailingComma() throws Exception
+    {
+        final String INPUT = "s,t\nd,e,\n";
+        final CsvSchema schema = MAPPER.schemaFor(StringPair.class);
+
+        MappingIterator<StringPair> it = MAPPER.readerFor(StringPair.class)
+                .with(schema)
+                .without(CsvParser.Feature.ALLOW_TRAILING_COMMA)
+                .readValues(INPUT);
+
+        it.nextValue();
+        try {
+            it.nextValue();
+            fail("Should not have passed");
+        } catch (JsonMappingException e) {
+            verifyException(e, "Too many entries: expected at most 2 (value #2 (0 chars) \"\")");
+        }
+
+        it.close();
+    }
+}